Since the Multiple Input Multiple Output (MIMO) technologies are important to an improvement of a peak rate and a system spectrum utilization ratio, all the radio access technology standards of Long Term Evolution (LTE), LTE-Advanced (LTE-A), etc., have been built based upon the MIMO and Orthogonal Frequency Division Multiplexing (OFDM) technologies. A gain performance of the MIMO technologies arises from a space freedom available in a multi-antenna system, since faster data transmission can be achieved using the space freedom, so one of the most important evolvements of the MIMO technologies being standardized is an extension of dimensions.
In order to further improve the gain performance of the MIMO technologies, the technologies of a large-scale antenna array have been introduced to a mobile communication system. The large-scale antenna array includes up to 128 antenna elements and up to 128 transceivers, or up to 256 antenna elements and up to 256 transceivers, or up to 512 antenna elements and up to 512 transceivers. If the large-scale antenna array is traditionally arranged as Radio Remote Units (RRUs) and passive antennas, and each antenna element is connected with a transceiver, then 128, 256, or 512 radio frequency cables will be necessitated, but it may be rather difficult to engineer such a large number of radio frequency cables, and too difficult to guarantee their reliability, so active antennas are typically arranged in the large-scale antenna array, which is referred to as a large-scale active antenna array.
For the large-scale active antennas, the antenna array is typically integrated with the RRU functions, and provided without any traditional antenna connectors, so the traditional radiation test method can not be used for testing.